This invention pertains to a windshield wiper system in which the wiper contact pressure on the window is adjustable.
German specification OS No. 3,314,456 describes a windshield wiper system in which the contact pressure of the wiper blade is adjusted by an actuator. The actuator is an adjusting rod guided in a bore of the wiper shaft, and is driven electromotively to vary the suspension point of a contact pressure spring of the wiper arm by way of a lever. The actuator includes sections formed as a toothed rack which meshes with a pinion. The actuator is thereby formed as a single piece and extends from the gear housing of the actuating drive through the wiper shaft to the working point on the lever, on which the contact pressure spring is suspended.
This adjusting mechanism occupies a relatively large space and does not have good efficiency. Short adjusting times cannot be achieved.
Smooth guidance of the relatively long actuator can not be ensured due to unavoidable tolerances. Thus in this construction relatively high friction has to be expected, so that accordingly high adjusting forces are needed and the motor has to be accordingly high-powered. If in the worst case the actuator locks, then the motor may be blocked and possibly destroyed.